Conventionally, a sheet processing apparatus is known which executes post processing such as a stapling processing on sheets loaded on a processing tray. In order to adjust deviation between the sheets loaded on the processing tray which are subjected to the post processing, the sheet processing apparatus includes a member for adjusting (horizontally aligning) the deviation of the sheet in a width direction and a member for adjusting (vertically aligning) the deviation in a direction orthogonal to the width direction of the sheet.